Hepatitis is a generic term for disease involving inflammation of the liver. A variety of agents can cause hepatitis, including viruses, drugs, toxins, and autoimmune disorders. Additionally, hepatitis can arise secondary to non liver-related disorders. Viral infection is the most common cause of hepatitis.
At least 8 different hepatitis viruses are believed to exist, and include the A, B, C, D, E, F, G and cryptogenic hepatitis viruses. The hepatitis viruses are spread through a number of different virus families. Of these viruses, hepatitis B virus (HBV, a hepadnavirus) and hepatitis C virus (HCV, a flavivirus) pose the greatest public health problem in industrialized countries. Both hepatitis B and C are bloodborne diseases, although both viruses may also be transmitted perinatally and via sexual contact.
Hepatitis B and C can each give rise to acute and chronic infections. A relatively low level of mortality is due to acute B and C hepatitis (primarily due to fulminant hepatitis). However, the chronic forms of each disease pose significant medical issues. HBV is the most prevalent chronic infectious disease in the world, and poses a substantially larger perinatal transmission risk than HCV, with 90% of children born to HBV-infected mothers becoming lifelong carriers. HCV is currently the leading cause of liver transplants in the United States.
Only about half of HBV infections, and even fewer HCV infections, are symptomatic in the acute phase, which typically presents with symptoms such as jaundice, fatigue, abdominal pain and/or loss of appetite. Subclinical infections can be detected using diagnostic testing for viral antigens and/or DNA.
The vast majority (95-98%) of adults infected with HBV resolve their disease and experience no further ill effects, although newborns are at substantial risk of developing a chronic infection, with approximately 80-90% of perinatally infected individuals developing chronic disease. Chronic HBV infection is typically asymptomatic, although some symptoms of acute hepatitis B may be present. The long term sequelae of chronic HBV infection include liver fibrosis/cirrhosis, liver cancer, liver failure and death.
Chronic HBV infection is a substantial public health issue in Asia, where comparatively large percentages of the population are chronically infected with HBV. Mirroring these high rates of chronic infection are rates of hepatocellular carcinoma (HCC), a liver cancer associated with chronic HBV infection.
In the U.S., acute HCV infections are substantially less common than acute HBV infections, by a factor of approximately ten. However, due to the substantially greater risk of progression to chronic infection (≧85%), the prevalence of chronic HCV infection is two to three times greater than that for chronic HBV infection. Additionally, HCV infection carries a much greater risk of the development of chronic liver disease and liver failure.
Although HBV and HCV are very different viruses, treatments for chronic infections with the two viruses are virtually identical. Currently available treatments for chronic hepatitis B and C infection are limited to interferons. Interferon α-2a, interferon α-2b and interferon alfacon-1 (a recombinant, non-naturally occurring interferon 1 variant) are currently used for the treatment of chronic hepatitis virus infection, although “combination” therapy with ribavirin (an anti-viral drug) and interferon α-2b has also been approved for the treatment of chronic hepatitis C. However, these drugs require frequent administration and are associated with a large number of side effects, including “flu-like” symptoms (e.g., fatigue, fever, myalgia), leukopenia, thrombocytopenia, nausea, vomiting, and arthralgia. One rare complication of interferon administration is hepatotoxicity, which can be fatal. Unfortunately, only about 40% of patients show any improvement with interferon treatment, and may relapse after treatment is completed.
Currently, a number of new drugs are being developed for treatment of chronic HBV infection, including interferon β, interferon γ, interleukin 2, thymosin, acyclovir, lamivudine (3TC), and granulocyte colony factor. These drugs typically require long courses of administration, and most are accompanied by significant side effects.
Administration of certain DNA sequences, generally known as immunostimulatory sequences or “ISS,” induces an immune response with a Th1-type bias as indicated by secretion of Th1-associated cytokines. The Th1 subset of helper cells is responsible for classical cell-mediated functions such as delayed-type hypersensitivity and activation of cytotoxic T lymphocytes (CTLs), whereas the Th2 subset functions more effectively as a helper for B-cell activation. The type of immune response to an antigen is generally influenced by the cytokines produced by the cells responding to the antigen. Differences in the cytokines secreted by Th1 and Th2 cells are believed to reflect different biological functions of these two subsets. See, for example, Romagnani (2000) Ann. Allergy Asthma Immunol. 85:9-18.
Administration of an immunostimulatory polynucleotide with an antigen results in a Th1-type immune response to the administered antigen. Roman et al. (1997) Nature Med. 3:849-854. For example, mice injected intradermally with Escherichia coli (E. coli) β-galactosidase (β-Gal) in saline or in the adjuvant alum responded by producing specific IgG1 and IgE antibodies, and CD4+ cells that secreted IL-4 and IL-5, but not IFN-γ, demonstrating that the T cells were predominantly of the Th2 subset. However, mice injected intradermally (or with a tyne skin scratch applicator) with plasmid DNA (in saline) encoding β-Gal and containing an ISS responded by producing IgG2a antibodies and CD4+ cells that secreted IFN-γ, but not IL-4 and IL-5, demonstrating that the T cells were predominantly of the Th1 subset. Moreover, specific IgE production by the plasmid DNA-injected mice was reduced 66-75%. Raz et al. (1996) Proc. Natl. Acad. Sci. USA 93:5141-5145. In general, the response to naked DNA immunization is characterized by production of IL-2, TNFα and IFN-γ by antigen-stimulated CD4+ T cells, which is indicative of a Th1-type response. This is particularly important in treatment of allergy and asthma as shown by the decreased IgE production. The ability of immunostimulatory polynucleotides to stimulate a Th1-type immune response has been demonstrated with bacterial antigens, viral antigens and with allergens (see, for example, WO 98/55495).
Other references describing ISS include: Krieg et al. (1989) J. Immunol. 143:2448-2451; Tokunaga et al. (1992) Microbiol. Immunol. 36:55-66; Kataoka et al. (1992) Jpn. J. Cancer Res. 83:244-247; Yamamoto et al. (1992) J. Immunol. 148:4072-4076; Mojcik et al. (1993) Clin. Immuno. and Immunopathol. 67:130-136; Branda et al. (1993) Biochem. Pharmacol. 45:2037-2043; Pisetsky et al. (1994) Life Sci. 54(2):101-107; Yamamoto et al. (1994a) Antisense Research and Development. 4:119-122; Yamamoto et al. (1994b) Jpn. J. Cancer Res. 85:775-779; Raz et al. (1994) Proc. Natl. Acad. Sci. USA 91:9519-9523; Kimura et al. (1994) J. Biochem. (Tokyo) 116:991-994; Krieg et al. (1995) Nature 374:546-549; Pisetsky et al. (1995) Ann. N.Y. Acad. Sci. 772:152-163; Pisetsky (1996a) J. Immunol. 156:421-423; Pisetsky (1996b) Immunity 5:303-310; Zhao et al. (1996) Biochem. Pharmacol. 51:173-182; Yi et al. (1996) J. Immunol. 156:558-564; Krieg (1996) Trends Microbiol. 4(2):73-76; Krieg et al. (1996) Antisense Nucleic Acid Drug Dev. 6:133-139; Klinman et al. (1996) Proc. Natl. Acad. Sci. USA. 93:2879-2883; Raz et al. (1996); Sato et al. (1996) Science 273:352-354; Stacey et al. (1996) J. Immunol. 157:2116-2122; Ballas et al. (1996) J. Immunol. 157:1840-1845; Branda et al. (1996) J. Lab. Clin. Med. 128:329-338; Sonehara et al. (1996) J. Interferon and Cytokine Res. 16:799-803; Klinman et al. (1997) J. Immunol. 158:3635-3639; Sparwasser et al. (1997) Eur. J. Immunol. 27:1671-1679; Roman et al. (1997); Carson et al. (1997) J. Exp. Med. 186:1621-1622; Chace et al. (1997) Clin. Immunol. and Immunopathol. 84:185-193; Chu et al. (1997) J. Exp. Med. 186:1623-1631; Lipford.et al. (1997a) Eur. J. Immunol. 27:2340-2344; Lipford et al. (1997b) Eur. J. Immunol. 27:3420-3426; Weiner et al. (1997) Proc. Natl. Acad. Sci. USA 94:10833-10837; Macfarlane et al. (1997) Immunology 91:586-593; Schwartz et al. (1997) J. Clin. Invest. 100:68-73; Stein et al. (1997) Antisense Technology, Ch. 11 pp. 241-264, C. Lichtenstein and W. Nellen, Eds., IRL Press; Wooldridge et al. (1997) Blood 89:2994-2998; Leclerc et al. (1997) Cell. Immunol. 179:97-106; Kline et al. (1997) J. Invest. Med. 45(3):282A; Yi et al. (1998a) J. Immunol. 160:1240-1245; Yi et al. (1998b) J. Immunol. 160:4755-4761; Yi et al. (1998c) J. Immunol. 160:5898-5906; Yi et al. (1998d) J. Immunol. 161:4493-4497; Krieg (1998) Applied Antisense Oligonucleotide Technology Ch. 24, pp. 431-448, C. A. Stein and A. M. Krieg, Eds., Wiley-Liss, Inc.; Krieg et al. (1998a) Trends Microbiol. 6:23-27; Krieg et al. (1998b) J. Immunol. 161:2428-2434; Krieg et al. (1998c) Proc. Natl. Acad. Sci. USA 95:12631-12636; Spiegelberg et al. (1998) Allergy 53(45S):93-97; Horner et al. (1998) Cell Immunol. 190:77-82; Jakob et al. (1998) J. Immunol. 161:3042-3049; Redford et al. (1998) J. Immunol. 161:3930-3935; Weeratna et al. (1998) Antisense & Nucleic Acid Drug Development 8:351-356; McCluskie et al. (1998) J. Immunol. 161(9):4463-4466; Gramzinski et al. (1998) Mol. Med. 4:109-118; Liu et al. (1998) Blood 92:3730-3736; Moldoveanu et al. (1998) Vaccine 16: 1216-1224; Brazolot Milan et al. (1998) Proc. Natl. Acad. Sci. USA 95:15553-15558; Broide et al. (1998) J. Immunol. 161:7054-7062; Broide et al. (1999) Int. Arch. Allergy Immunol. 118:453-456; Kovarik et al. (1999) J. Immunol. 162:1611-1617; Spiegelberg et al. (1999) Pediatr. Pulmonol. Suppl. 18:118-121; Martin-Orozco et al. (1999) Int. Immunol. 11:1111-1118; EP 468,520; WO 96/02555; WO 97/28259; WO 98/16247; WO 98/18810; WO 98/37919; WO 98/40100; WO 98/52581; WO 98/55495; WO 98/55609 and WO 99/11275. See also Elkins et al. (1999) J. Immunol. 162:2291-2298, WO 98/52962, WO 99/33488, WO 99/33868, WO 99/51259 and WO 99/62923. See also Zimmermann et al. (1998) J. Immunol. 160:3627-3630; Krieg (1999) Trends Microbiol. 7:64-65; U.S. Pat. Nos. 5,663,153, 5,723,335, 5,849,719 and 6,174,872. See also WO 99/56755, WO 00/06588, WO 00/16804; WO 00/21556; WO 00/67023 and WO 01/12223.
There exists a need in the art for effective treatments of acute and chronic hepatitis B and C.
All publications and patent applications cited herein are hereby incorporated by reference in their entirety.